According to Rebbi a Kohen may delay looking at a Nega for a purpose other than a Mitzvah.
A Kohen may not look at a Nega at night.
A Kohen that is blind in one eye may not look at a Nega.
Rebbi Meir says that a person may transfer the bones of his father on Mo'ed because the joy of the Mo'ed will temper the sadness of the transfer of the bones. Rebbi Yosi disagrees.
A person should not hire someone to eulogize a deceased relative within thirty days of Yom Tov. (1)
It is forbidden to dig graves on Chol ha'Mo'ed but an already dug grave may be altered.
It is permitted to dig a laundry pool on Chol ha'Mo'ed.
It is permitted to make a coffin on Chol ha'Mo'ed if it is made in the same courtyard in which the body is located. Rebbi Yehudah permits it only if the panels were prepared prior to Yom Tov. (2)
It is forbidden to get married on Yom Tov because it is joyful. (3)
A BIT MORE
1. According to Rav the reason for the prohibition of eulogizing within thirty days of the Yom Tov is because of an incident that occurred. Someone used money that was set aside for Aliyah l’Regel to pay a eulogizer and as a result did not go to Yerushalayim for the Regel. According to Shmuel the reason is because a deceased is not forgotten from the heart for thirty days.
2. It is permitted to do all of the necessities of a deceased on Chol ha'Mo'ed including cutting hair, washing clothes and making the coffin.
3. The Amora'im give various reasons for the prohibition to get married on the Mo'ed. The reasons are: that it would be mixing one joy with another, because it would be an abandonment of the joy of Yom Tov, because a marriage takes a lot of strenuous preparation, or because it would result in a reduction of Pirya v’Rivya since couples would delay getting married until the Mo'ed.
The Gemara says according to one opinion the reason why it is forbidden to get married on the Mo'ed is because this would be mixing one joy with another. Tosfos says that the Yerushalmi learns this out from the Pasuk in Parshas Vayetzei in which Lavan tells Yakov, “Complete this week and she will also be given to you”. Yakov delayed the entire week of Sheva Berachos before he married Rachel. The reason for the prohibition to mix one joy with another is the same as the principle ‘Mitzvos should not be done in groups’. A person should put his entire heart into a Mitzvah without being distracted by another Mitzvah. So too a person should have his entire heart on the joy of Yom Tov without a distraction from another joy. The Mordechai says that for the same reason the Minhag is not to marry off two siblings at the same time.
It is forbidden to get married on the Mo'ed whether the bride is a Besulah or a widow and it is forbidden to do Yibum. (Shulchan Aruch OC 546:1)
The reason for the prohibition is because it is forbidden to mix one joy with another and that reason applies even if the marriage takes place without a festive meal. The Acharonim say that the prohibition of mixing one joy with another only applies to the same person. Therefore it is permitted to marry off two orphans at once. However the Minhag is not to marry off two siblings at the same time. (Mishnah Berurah)